The symptoms as mentioned in your post suggest that you might be having gastritis
associated with chronic constipation
Though symptomatic relief can be obtained with intake of antacid preparation, the underlying cause needs to be treated.
Regarding the problem of constipation, the causes can be many, such as:
The causes of constipation can be:
1. Any pathology/ sub acute obstruction in the Gastrointestinal tract
2. Irritable bowel syndrome- constipation predominant type.
3. Functional cause- due to decreased gastric motility
4. Inadequate intake of fluids and fiber rich diet- as suspected by your doctor
5. Hormonal & Metabolic causes, etc.
So, kindly consult a Gastroenterologist
& get a proper physical examination done.
Investigations like complete blood count
scan of abdomen, Endoscopy & contrast studies will be helpful to rule out any pathological cause for your symptoms.
There is no need to worry, you will be fine.
Till then, maintain adequate hydration & proper nutrition status.
Wishing a good health.